The present invention relates to processes and intermediates for the preparation of oxophthalazinyl acetic acids and analogues thereof. The latter compounds are aldose reductase inhibitors and are useful in preventing or alleviating chronic complications associated with diabetes.
Aldose reductase inhibitors that may be prepared by the processes of the present invention are disclosed in U.S. Ser. No. 07/263,577, filed Oct. 27, 1988 and European Patent Application Publication Number 222576. Nitriles that are used as starting materials in the processes of the present invention are disclosed in European Patent Application Publication Number 0295051.
West German Patent Application DE 3337859 refers to preparation of benzothiazole derivatives by cyclization of 2-substituted aniline or nitrobenzene compounds with thioamide derivatives.
International Application PCT/US88/00110, filed Jan. 19, 1988 refers to 1H-indazole-3-acetic acids as aldose reductase inhibitors.